External systems for detecting implantable neurostimulation leads and devices, and methods of using same

ABSTRACT

Embodiments herein include an external system and method to detect an implanted lead coupled to an implanted neurostimulation device (INSD). The system and method comprise a handheld probe having electrodes configured to be positioned external to a surface of a patient and proximate to a region of the patient having the implanted lead for an implanted INSD. The electrodes are configured to measure a stimulation output from the implanted lead of the INSD. The system and method include a controller coupled to the electrodes to receive measured signals from the electrodes. The measured signals represent the stimulation output of the INSD. The controller processes the measured signals to obtain lead information. The system includes a user interface to present the lead information to a user. The lead information is indicative of at least one of an operation of the lead and a position of the lead.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/596,592, filed Aug. 28, 2012, which claims the benefit of U.S.Provisional Application No. 61/538,018, filed Sep. 22, 2011, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

Embodiments of the present invention generally relate toneurostimulation systems, and more particularly to methods and systemsto monitor an implanted lead and implanted neurostimulation device.

Neurostimulation (NS) systems are systems that generate electricalpulses and deliver the pulses to nerve tissue to treat a variety ofdisorders. Spinal cord stimulation (SCS) is the most common type ofneurostimulation. In SCS, electrical pulses are delivered to nervetissue in the spine typically for the purpose of chronic pain control.While a precise understanding of the interaction between the appliedelectrical energy and the nervous tissue is not fully appreciated, it isknown that application of an electrical field to spinal nervous tissuecan effectively mask certain types of pain transmitted from regions ofthe body associated with the stimulated nerve tissue. Applyingelectrical energy to the spinal cord associated with regions of the bodyafflicted with chronic pain can induce “paresthesia” (a subjectivesensation of numbness or tingling) in the afflicted bodily regions.Thereby, paresthesia can effectively mask the transmission of non-acutepain sensations to the brain.

An NS system generally includes a NS device (NSD) that includes a pulsegenerator, with the NSD coupled to one or more stimulation leads. Astimulation lead includes a lead body of insulative material thatencloses wire conductors. The distal end of the stimulation leadincludes multiple electrodes that are electrically coupled to the wireconductors. The proximal end of the lead body includes multipleterminals, which are also electrically coupled to the wire conductorsthat are adapted to receive electrical pulses. The distal end of arespective stimulation lead is implanted within a desired area, such asthe epidural space, to deliver the electrical pulses to the appropriatenerve tissue, such as within the spinal cord that corresponds to thedermatome(s) in which the patient experiences chronic pain. Thestimulation leads are then tunneled to another location within thepatient's body to be electrically connected with a pulse generator or,alternatively, to an “extension.”

The NS device is typically implanted within a subcutaneous pocketcreated during the implantation procedure. In SCS, the subcutaneouspocket is typically disposed in a lower back region, althoughsubclavicular implantations and lower abdominal implantations arecommonly employed for other types of neuromodulation therapies.

The NS device is typically implemented using a metallic housing thatencloses circuitry for generating the electrical pulses, controlcircuitry, communication circuitry, a rechargeable battery, etc. Thepulse generating circuitry is coupled to one or more stimulation leadsthrough electrical connections provided in a “header” of the pulsegenerator. Specifically, feedthrough wires typically exit the metallichousing and enter into a header structure of a moldable material. Withinthe header structure, the feedthrough wires are electrically coupled toannular electrical connectors. The header structure holds the annularconnectors in a fixed arrangement that corresponds to the arrangement ofterminals on a stimulation lead.

After implantation, it may become desirable to monitor variousparametric properties of the NS system. For example, it may be desirableto analyze the operation of the NS device, such as the discharge mode,pulse sequency, pulse width and frequency for the stimulation output ofthe NS device. Further, it may become desirable to locate the NS leadand more specifically, to locate the position and/or identityinoperative and operative electrodes on the NS lead. Afterimplementation, the potential exists for NS leads to move or migratewithin the patient. Heretofore, there has been no reliable and practicalmechanism to readily identify lead migration. Also, there is no reliableand practical method for a physician or representative to locate thelead's position in connection with reprogramming or physicalintervention. Today, physicians use fluoroscopy systems to locate a leadthat has moved within the patient. Once the new position of the lead isidentified, the physician then reprograms the lead, such as to use adifferent set of electrodes on the lead to deliver the stimulus output.This method exposes the patient to radiation each time a fluoroscopy isperformed, which is not desirable.

Also, presently there is no reliable and practical way to identify leadmalfunctions. Lead malfunctions may occur due to physical failure orbreaks within the lead conduction and/or electrical failures within theNS device. Today when a physical failure or break causes a lead tooperate intermittently or not at all, the intermittent and open leadsare not easily diagnosable down to the electrode.

Further, today no tool exists that enables data logging for research toenable patient anomalies to be recorded in connection with stimulationoutputs while an NS lead is in the patient. Also, today problems occurin the emergency medical field because an unconscious person cannotinform an EMT that the person has an implantable device, and cannotinform the EMT of the location of the implantable device. Hospitalsusing MRI's and X-ray machines may not have a quick method ofdetermining what type of device the patient has within them, nor thelocation of the device.

A need remains for systems and methods that detect an implanted leadand/or an implanted neurostimulation device and that provide parametricinformation in connection therewith.

SUMMARY

Embodiments of the present invention include an external detector with aprobe that has an instrumentation amplifier coupled to two or moreclosely spaced surface electrodes. The probe surface electrodes searchfor implanted electrodes of an NS lead by externally contacting the skinof the patient at different distances from the electrical source andobtaining measurements that are used to locate the NS lead activeelectrodes or electrical field output source. The external deviceaccurately amplifies actual stimulation and displays information, suchas graphs, oscilloscope images and the like, that are indicative ofstimulation output from the implanted electrodes. For example, thedisplay may present a graph corresponding to the electrical occurrence,where the amplitude of the graph corresponds to the stimulation output.The amplitude of the measured signal increases as the probe moves closerto the implanted electrodes that are generating the stimulation outputbecause the electrical field grows stronger when the external probeelectrodes are moved closer to the stimulation source.

Embodiments herein include an external system to detect an implantedlead coupled to an implanted neurostimulation device (INSD). The systemcomprises a handheld probe having electrodes configured to be positionedexternal to a surface of a patient and proximate to a region of thepatient having the implanted lead for an implanted INSD. The electrodesare configured to measure a stimulation output from the implanted leadof the INSD. The system includes a controller coupled to the electrodesto receive measured signals from the electrodes. The measured signalsrepresent the stimulation output of the INSD. The controller processesthe measured signals to obtain lead information. The system includes auser interface to present the lead information to a user. The leadinformation is indicative of at least one of an operation of the leadand a position of the ISND lead.

Optionally, the lead information may include at least one of dischargemode, pulse width and frequency for the stimulation output of the INSD;a presence, signal strength, duration and shape for the stimulationoutput of the INSD; electrical occurrence of, and electrical anomaliesin, the stimulation output of the INSD; i) information to locate thelead in the patient and ii) information to identify improper operationof the lead.

Optionally, the external surface electrodes include first and secondelectrode inputs closely spaced proximate to one another to be movedalong skin of the patient while locating the lead. An amplifier comparesthe measured signals to obtain a difference signal, the differencesignal increasing as the electrodes move closer to a source of thestimulation output.

In other embodiments, a method is provided to detect an implanted leadof an implanted neurostimulation device (INSD). The method comprisespositioning a handheld probe having electrodes external to a surface ofa patient and proximate to a region of the patient having the implantedlead for an implanted INSD and configuring the electrodes to measure astimulation output from the implanted lead of the INSD. The methodfurther comprises receiving measured signals from the electrodes, wherethe measured signals are representative of the stimulation output of theINSD; and processing the measured signals to obtain INSD leadinformation. The method then presents the lead information to a user,where the lead information is indicative of at least one of an operationof the lead and a position of the ISND lead.

Optionally, the presenting operation includes displaying to the user agraphical representation of the measured stimulation output including apulse sequence having at least one pulse void therein corresponding to alocation in the pulse sequence associated with a failed electrode.Optionally, the presenting operation includes displaying to the user agraphical representation of a measured pulse sequence that includes ablank area in the pulse sequence where a pulse should have beenmeasured, but did not occur due to a faulty electrode. Optionally, thepresenting operation includes co-displaying measured and programmedstimulation outputs for comparison by the user to determine where afault exists.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a neurostimulation system according to somerepresentative embodiments.

FIGS. 2A-2C respectively depicts stimulation portions for inclusion atthe distal end of a lead according to some representative embodiments.

FIG. 3 illustrates a system for detecting NS devices and NS leads inaccordance with an embodiment.

FIG. 4A illustrates an exemplary side view of a tip portion of a probewhen in use to monitor or locate an NS lead in accordance with anembodiment.

FIG. 4B-4E illustrates an exemplary side view of a tip portion of aprobe when in use to monitor or locate an NS lead in accordance with anembodiment.

FIG. 5 illustrates a comparator circuit utilized in accordance with anembodiment.

FIG. 6 illustrates an example of a difference signal that may be outputby the comparator in accordance with an embodiment.

FIG. 7 illustrates an alternative embodiment in which a probe isutilized to sense a patch type lead in accordance with an embodiment.

FIG. 8 illustrates a process implemented in accordance with anembodiment to detect and analyze implanted NS leads and NS devices inaccordance with an embodiment.

FIG. 9 illustrates a process carried in connection with identifyingfaults in leads in accordance with an embodiment.

FIG. 10A-10C illustrates a pulse output by the lead and sensed by thesurface electrodes.

FIG. 11 illustrates a process carried in connection with identifyingshort circuits in an NS device header.

FIG. 12 illustrates exemplary windows with the types of information thatmay be presented to the user on the display.

DETAILED DESCRIPTION

Embodiments herein provide a non-intrusive tool to display electricaloccurrence, diagnose electrical anomalies, and/or locate active leads inthe patient while an NS device is operating in the patient. Also theexternal detector affords the emergency medical field a quick responsesmall hand held tool to diagnose malfunctioning electrical medicaldevices. Embodiments described here can be implemented in various ways,such as a handheld wireless device utilizing a pickup coil and circuitryto amplify and digitize the measured signal into readable measurementssuch as discharge mode, pulse width, and frequency. As another exemplaryimplementation, the external detector can be performed in a contactlessmanner. The detector may display the presence of the measured signalsand/or quantify signal strength, duration, shape and other relatedparametric properties, thereby enabling non-intrusive diagnosis of themedical device operation, performance and strength thus givingoperational confirmation.

Embodiments herein provide a handheld stimulation analysis and leadlocator device. Other applications may include a computer interfacewhich affords real time analysis and physician program tuning. Theanalysis and/or tuning may utilize computer models that provide data forcreating or tuning more efficient electrical fields for the NS device,thereby enabling more precise programming for pain managementpersonalized to the individual patient. Embodiments herein provide auser friendly tool for physicians and a tool that may facilitatestudies. These tools and the studies based thereon may enable newproducts to become more efficient and easier to use. These tools and thestudies based thereon may enable programmable devices to be more readilyavailable on the market.

FIG. 1 depicts a neurostimulation (NS) system 100 that generateselectrical pulses for application to tissue of a patient according toone embodiment. For example, NS system 100 may be adapted to stimulatespinal cord tissue, peripheral nerve tissue, deep brain tissue, corticaltissue, cardiac tissue, digestive tissue, pelvic floor tissue, or anyother suitable tissue within a patient's body.

NS system 100 includes an implantable NS device 150 that is adapted togenerate electrical pulses for application to tissue of a patient. Theimplantable NS device 150 typically comprises a metallic housing thatencloses controller 151, pulse generating circuitry 152, charging coil153, battery 154, far-field and/or near field communication circuitry155, battery charging circuitry 156, switching circuitry 157, etc. ofthe device. Controller 151 typically includes a microcontroller or othersuitable processor for controlling the various other components of thedevice. Software code is typically stored in memory of the NS device 150for execution by the microcontroller or processor to control the variouscomponents of the device.

The NS device 150 may comprise a separate or an attached extensioncomponent 170. If extension component 170 is a separate component,extension component 170 may connect with the “header” portion of NSdevice 150 as is known in the art. If extension component 170 isintegrated with NS device 150, internal electrical connections may bemade through respective conductive components. Within NS device 150,electrical pulses are generated by pulse generating circuitry 152 andare provided to switching circuitry 157. The switching circuit connectsto outputs of NS device 150. Electrical connectors (e.g., “Bal-Seal”connectors) within connector portion 171 of extension component 170 orwithin the IPG header may be employed to conduct the stimulation pulses.The terminals of one or more stimulation leads 110 are inserted withinconnector portion 171 or within the header for electrical connectionwith respective connectors. Thereby, the pulses originating from NSdevice 150 are provided to stimulation lead 110. The pulses are thenconducted through the conductors of lead 110 and applied to tissue of apatient via electrodes 111. Any suitable known or later developed designmay be employed for connector portion 171.

For implementation of the components within NS device 150, a processorand associated charge control circuitry for an implantable pulsegenerator is described in U.S. Pat. No. 7,571,007, entitled “SYSTEMS ANDMETHODS FOR USE IN PULSE GENERATION,” which is incorporated herein byreference. Circuitry for recharging a rechargeable battery, of animplantable pulse generator using inductive coupling and externalcharging circuits are described in U.S. Pat. No. 7,212,110, entitled“IMPLANTABLE DEVICE AND SYSTEM FOR WIRELESS COMMUNICATION,” which isincorporated herein by reference.

An example and discussion of “constant current” pulse generatingcircuitry is provided in U.S. Patent Publication No. 20060170486entitled “PULSE GENERATOR HAVING AN EFFICIENT FRACTIONAL VOLTAGECONVERTER AND METHOD OF USE,” which is incorporated herein by reference.One or multiple sets of such circuitry may be provided within NS device150. Different pulses on different electrodes may be generated using asingle set of pulse generating circuitry using consecutively generatedpulses according to a “multi-stimset program” as is known in the art.Complex pulse parameters may be employed such as those described in U.S.Pat. No. 7,228,179, entitled “Method and apparatus for providing complextissue stimulation patterns,” and International Patent PublicationNumber WO/2001/093953 A1, entitled “NEUROMODULATION THERAPY SYSTEM,”which are incorporated herein by reference. Alternatively, multiple setsof such circuitry may be employed to provide pulse patterns that includesimultaneously generated and delivered stimulation pulses throughvarious electrodes of one or more stimulation leads as is also known inthe art. Various sets of parameters may define the pulse characteristicsand pulse timing for the pulses applied to various electrodes as isknown in the art. Although constant current pulse generating circuitryis contemplated for some embodiments, any other suitable type of pulsegenerating circuitry may be employed such as constant voltage pulsegenerating circuitry.

Neurostimulation lead(s) 110 may comprise a lead body of insulativematerial about a plurality of conductors within the material that extendfrom a proximal end of lead 110 to its distal end. The conductorselectrically couple a plurality of electrodes 111 to a plurality ofterminals (not shown) of lead 110. The terminals are adapted to receiveelectrical pulses and the electrodes 111 are adapted to applystimulation pulses to tissue of the patient. Also, sensing ofphysiological signals may occur through electrodes 111, the conductors,and the terminals. Additionally or alternatively, various sensors (notshown) may be located near the distal end of stimulation lead 110 andelectrically coupled to terminals through conductors within the leadbody 172. Stimulation lead 110 may include any suitable number ofelectrodes 111, terminals, and internal conductors.

FIGS. 2A-2C respectively depict stimulation portions 200, 225, and 250for inclusion at the distal end of lead 110. Stimulation portion 200depicts a conventional stimulation portion of a “percutaneous” lead withmultiple ring electrodes. Stimulation portion 225 depicts a stimulationportion including several “segmented electrodes.” The term “segmentedelectrode” is distinguishable from the term “ring electrode.” As usedherein, the term “segmented electrode” refers to an electrode of a groupof electrodes that are positioned at the same longitudinal locationalong the longitudinal axis of a lead and that are angularly positionedabout the longitudinal axis so they do not overlap and are electricallyisolated from one another. Example fabrication processes are disclosedin U.S. Patent Publication No. 20110072657, entitled, “METHOD OFFABRICATING STIMULATION LEAD FOR APPLYING ELECTRICAL STIMULATION TOTISSUE OF A PATIENT,” which is incorporated herein by reference.Stimulation portion 250 includes multiple planar electrodes on a paddlestructure.

Although not required for all embodiments, the lead bodies of lead(s)110 and extension component 170 may be fabricated to flex and elongatein response to patient movements upon implantation within the patient.By fabricating lead bodies according to some embodiments, a lead body ora portion thereof is capable of elastic elongation under relatively lowstretching forces. Also, after removal of the stretching force, the leadbody is capable of resuming its original length and profile. Forexample, the lead body may stretch 10%, 20%, 25%, 35%, or even up orabove to 50% at forces of about 0.5, 1.0, and/or 2.0 pounds ofstretching force.

The ability to elongate at relatively low forces may present one or moreadvantages for implantation in a patient. For example, as a patientchanges posture (e.g., “bends” the patient's back), the distance fromthe implanted pulse generator to the stimulation target locationchanges. The lead body may elongate in response to such changes inposture without damaging the conductors of the lead body ordisconnecting from pulse generator. Also, deep brain stimulationimplants, cortical stimulation implants, and occipital subcutaneousstimulation implants usually involve tunneling of the lead body throughtissue of the patient's neck to a location below the clavicle. Movementof the patient's neck subjects a stimulation lead to significant flexingand twisting which may damage the conductors of the lead body. Due tothe ability to elastically elongate responsive to movement of thepatient's neck, certain lead bodies according to some embodiments arebetter adapted for such implants than some other known lead bodydesigns. Fabrication techniques and material characteristics for “bodycompliant” leads are disclosed in greater detail in U.S. ProvisionalPatent Application Ser. No. 60/788,518, entitled “Lead BodyManufacturing,” filed Mar. 31, 2006, which is incorporated herein byreference.

Controller device 160 may be implemented to recharge battery 153 of NSdevice 150 (although a separate recharging device could alternatively beemployed). A “wand” 165 may be electrically connected to controllerdevice through suitable electrical connectors (not shown). Theelectrical connectors are electrically connected to coil 166 (the“primary” coil) at the distal end of wand 165 through respective wires(not shown). Typically, coil 166 is connected to the wires throughcapacitors (not shown). Also, in some embodiments, wand 165 may compriseone or more temperature sensors for use during charging operations.

The patient then places the primary coil 166 against the patient's bodyimmediately above the secondary coil (not shown), i.e., the coil of theimplantable medical device. Preferably, the primary coil 166 and thesecondary coil are aligned in a coaxial manner by the patient forefficiency of the coupling between the primary and secondary coils.Controller 160 generates an AC-signal to drive current through coil 166of wand 165. Assuming that primary coil 166 and secondary coil aresuitably positioned relative to each other, the secondary coil isdisposed within the field generated by the current driven throughprimary coil 166. Current is then induced in secondary coil. The currentinduced in the coil of the implantable pulse generator is rectified andregulated to recharge battery 153 by charging circuitry 154. Chargingcircuitry 154 may also communicate status messages to controller 160during charging operations using pulse-loading or any other suitabletechnique. For example, controller 160 may communicate the couplingstatus, charging status, charge completion status, etc.

External controller device 160 is also a device that permits theoperations of NS device 150 to be controlled by user after NS device 150is implanted within a patient, although in alternative embodimentsseparate devices are employed for charging and programming. Also,multiple controller devices may be provided for different types of users(e.g., the patient or a clinician). Controller device 160 can beimplemented by utilizing a suitable handheld processor-based system thatpossesses wireless communication capabilities. Software is typicallystored in memory of controller device 160 to control the variousoperations of controller device 160. Also, the wireless communicationfunctionality of controller device 160 can be integrated within thehandheld device package or provided as a separate attachable device. Theinterface functionality of controller device 160 is implemented usingsuitable software code for interacting with the user and using thewireless communication capabilities to conduct communications with IPG150.

Controller device 160 preferably provides one or more user interfaces toallow the user to operate NS device 150. The user interfaces may permitthe user to move electrical stimulation along and/or across one or morestimulation leads using different electrode combinations, for example,as described in U.S. Patent Application Publication No. 2009/0326608,entitled “METHOD OF ELECTRICALLY STIMULATING TISSUE OF A PATIENT BYSHIFTING A LOCUS OF STIMULATION AND SYSTEM EMPLOYING THE SAME,” which isincorporated herein by reference. Also, controller device 160 may permitoperation of IPG 150 according to one or more stimulation programs totreat the patient's disorder(s). Each stimulation program may includeone or more sets of stimulation parameters including pulse amplitude,pulse width, pulse frequency or inter-pulse period, pulse repetitionparameter (e.g., number of times for a given pulse to be repeated forrespective stimset during execution of program), etc. IPG 150 modifiesits internal parameters in response to the control signals fromcontroller device 160 to vary the stimulation characteristics ofstimulation pulses transmitted through stimulation lead 110 to thetissue of the patient. Neurostimulation systems, stimsets, andmulti-stimset programs are discussed in PCT Publication No. WO 01/93953,entitled “NEUROMODULATION THERAPY SYSTEM,” and U.S. Pat. No. 7,228,179,entitled “METHOD AND APPARATUS FOR PROVIDING COMPLEX TISSUE STIMULATIONPATTERNS,” which are incorporated herein by reference.

FIG. 3 illustrates an external detector system 300 to detect animplanted lead and/or operation of an implanted neurostimulation devicein accordance with embodiments herein. The detector system 300 locatesleads and/or devices in numerous regions of the patient, such as alongthe spinal column, stomach, organs, muscles, inside the skull, along thebrain stem and the like. The system 300 includes a detector 330connected to a handheld probe 302 that has surface electrodes 304configured to be positioned proximate and external to a surface of apatient. The probe 302 also includes a transceiver 320 and aninput/output (I/O) port 322. The surface electrodes 304 and 305 arelocated, by the user, proximate to a region 306 of the patient having animplanted lead 308 for an implanted NS device 310. The probe 302includes first and second electrodes 304 and 305 that are closely spacedproximate to one another and separated by an inter-electrode gap 352.The surface electrodes 304 and 305 measure a stimulation output from theimplanted lead 308. The probe 302 includes signal processing circuitry(SPC) 312 that is connected through lines 314 and 315 to the surfaceelectrodes 304 and 305. The SPC 312 receives and processes measuredsignals from the surface electrodes 304 and 305. The measured signalsare representative of the stimulation output of the implanted lead 308.The measured signals may have positive or negative amplitude; high,medium or low amplitude; high, medium or low frequency and the like. TheSPC 312 may include only a few simple electrical components, or mayinclude a sophisticated signal processing board with a microprocessorand memory. The SPC 312 may include an A/D converter to digitizemeasured signals and a processor module to analyze the digitizedmeasured signals.

The system 300 analyzes the measured signals received along lines 314and 315 to obtain implanted lead information. For example, the SPC 312may filter, amplify and digitize the measured signals received alonglines 314 and 315 and obtain a difference signal there between. Thedifference signal is one example of implanted lead information. Asexplained hereafter, implanted lead information may be calculated bycontroller 336 of the detector 330 as well or instead of by the SPC 312.

The SPC 312 may include an amplifier (e.g., amplifier 500 in FIG. 5)that compares the measured signals to obtain a continuous differencesignal as the probe 302 is moved. The difference signal increases as thesurface electrodes 304, 305 are moved away from a source of thestimulation output. The difference signal decreases as the surfaceelectrodes 304, 305 are moved closer to a source of the stimulationoutput. The difference signal is at a minimum when the surfaceelectrodes 304, 305 are centered over an active implanted electrode.

Optionally, the probe 302 may include an additional grounding electrode307 connected by line 309 to the probe 302. The grounding electrode 307may be attached to another region of the patient (e.g., leg, arm, waist,chest), while the line 309 may be joined to the housing of the probe302, to the signal processing circuitry 312 or otherwise to establish areference ground.

The system 300 includes a non-implantable external detector 330connected to the probe 302 over a physical two-way communications line344 and/or a two-way wireless link 346. The detector 330 includes an I/Oport 342. The line 344 is connected between the I/O ports 342 and 322.The detector 330 includes a transceiver 340 that communicates with thetransceiver 320 over the wireless link 346. The physical line 344 may beone or more coaxial cables, USB lines, optical connections or any othertype of link(s) that supports transfer of high speed, large bandwidthanalog or digital signals and/or data. The wireless link 346 may be aninfrared link, an optical link, an RF link, a microwave link, a cellularlink or any other type of link any other type of link(s) that supportstransfer of high speed, large bandwidth analog or digital signals and/ordata. The system 300 may utilize various protocols to manage conveyanceof the signals and data between the detector 330 and the probe 302.

The detector 330 and probe 302 may represent a handheld portable devicethat can be easily carried by a user such as a technician, doctor, EMTand the like. Optionally, the detector 330 may constitute a cell phone,PDA, laptop computer, tablet-type computer, desk top computer and thelike. Optionally, the detector 330 and probe 302 may be combined into acommon housing to form a single integrated portable handheld device.

The probe 302 may convey various types of implanted lead information tothe detector 330. For example, the probe 302 may simply convey themeasured signals to the detector 330. Alternatively, the probe 302 mayconvey, to the detector 330, a difference between the measured signals,and/or analysis data derived from the measured signals (e.g., lead faultresults, lead location, electrode status).

The detector 330 also includes a controller 336 and memory 338. Thememory 338 may store signals, information and data conveyed to and fromthe probe 302, such as the measured signals, difference signals,analysis data and the like. The memory 338 also stores software used toimplement various analysis methods by the controller 336.

The detector 330 includes a user interface 332 that includes a display334 to present the implanted lead information to a user and user input335 to receive instructions and inputs from the user. The leadinformation may be indicative of at least one of an operation of thelead and the position of the lead. The lead information may include atleast one of discharge mode, pulse width and frequency for stimulationoutput of the NS device 150. The lead information may include at leastone a presence, signal strength, duration and shape for the stimulationoutput of the NS device 150 at select electrodes or at each electrode.The lead information may include at least one electrical occurrence of,and electrical anomalies in, the stimulation outputs of the NS device150 at select electrodes or at each electrode. Optionally, the leadinformation may include information to locate the NS lead in the patientand/or information to identify improper operation of the NS lead.

The display 334 may illustrate a graph plotting the positive or negativeamplitude of the difference signal along a vertical axis and time alongthe horizontal axis. As the probe 302 is moved along the patient's skin,the amplitude of the difference signal changes from a high level to alow level to near zero as the skin electrodes 304, 305 are moved from adistal, non-aligned position to an aligned position, proximate to thelead. When the display presents a near-zero graph, this indicates thatthe surface electrodes 304, 305 are generally centered over a source ofthe stimulation output. As the probe 302 is moved up/back or left/right,the signal displayed will increase/decrease and may reach a null valuewhen centered over the implanted lead.

FIG. 4A illustrates an exemplary side view of a tip portion of probe 302when in use to monitor or locate an NS lead 408. As shown in FIG. 4A, anNS lead 408 is located below the skin surface 410 of a patient. The NSlead 408 includes multiple implanted electrodes 421-428 that areseparately controlled by, and individually coupled to, an NS device (notshown) that may be also implanted in the patient. The implantedelectrodes 421-428 may be individually controlled to deliver differenttypes of pulses with different polarities, pulse widths, amplitudes,pulse shapes and the like. As a further example, a portion of theelectrodes 421-428 may not be utilized at all and thus may deliver nostimulus pulses, such as denoted by the zeros next to the electrodes 425and 426. Optionally, only one of electrodes 421-428 may deliver astimulation output at one point in time, thereby permitting eachelectrode 421-428 to be individually analyzed. In the example of FIG.4A, polarity signs are noted next to electrodes 421-424 and 427-428 toindicate that positive or negative pulses are output there from. It isunderstood that any combination of pulse shapes, pulse polarities, pulsewidths and the like may be utilized, as well as numerous alternativecombinations of the electrodes 421-428 in order to deliver a desiredneurostimulation output and/or perform a lead analysis test by system300.

As illustrated in FIG. 4A, the tip or distal portion of the probe 302 islocated against the skin surface 410 of a patient. The surfaceelectrodes 304-305 are located proximate or immediately adjacent to theskin surface 410 of the patient in order to facilitate sensing ofelectrical activity from the implanted electrodes 421-428. Duringoperation, the probe 302 and electrodes 304-305 are moved along the skinof the patient while the NS lead outputs a programmed stimulus output.Measured signals sensed at the electrodes 304 and 305 may be compared orotherwise analyzed to obtain lead information. As the probe 302 is movedalong the skin surface 410, such as in the direction denoted by thearrow 430, the measured signals at electrodes 304-305 vary and similarlycause the lead information to vary. By comparing the lead informationderived from sensing at the electrodes 304 and 305, various informationmay be determined about the NS lead 408 such as location, operationalstatus and the like.

In the example of FIG. 4A, the distal portion of the probe 302 includesa patient engaging surface 350 configured to be located against thepatient skin 410. Optionally, a conductive material may be providedbetween the probe surface 350 and the patient skin 410 to facilitateconduction of electrical signals through the patient skin 410 to theelectrodes 304-305. The electrodes 304-305 are separated by aninter-electrode gap 352 (e.g., 2 mm, 4 mm, 8 mm) about a central axis454. The inter-electrode gap 352 may be adjusted to achieve a particulartype of performance and/or achieve sensitivity to different types ofelectrodes. As another example, the inter-electrode gap 352 may beselected such that, when the probe is used with certain types ofimplanted electrodes, it avoids inversion of the source signal whenmeasurements are taken at the strongest point in the field strength. Alarge inter-electrode gap 352 between electrode 304 and 305 may causeamplification of the largest difference from either the inverting ornon-inverting input to the comparator 502 (FIG. 5). A smallerinter-electrode gap 352 may be desired when trying to measure fieldstrength along a scan direction that is parallel to a source signal.

FIGS. 4B-4D illustrate bottom plan views of the probe skin contactsurfaces formed in accordance with embodiments of the present invention.In FIG. 4B, a probe 435 has a skin contact surface 436 and a handle 444.The signal processing circuitry, I/O module and transceiver are locatedat 446 in the handle 444. The surface 436 has an electrode pair 438 and439 located along a scan axis 442. An opening 440 may be providedthrough the probe 435 at a center point between the electrodes 438-439.A user may make a mark on the patient's skin, such as with a grease pinor marker through the opening 440. As another option, the opening 440may be used during a medical procedure, such as to insert a biopsyneedle or probe through the opening into the patient to manipulate orotherwise engage a desired implanted electrode or location on the lead.Longitudinal and lateral scan axes 442 and 441 may be provided asindicia on the top and bottom surfaces of the probe 435 to assist thephysician in guiding movement of the probe 435 during scanning.

The electrodes may have any desired shape, such as oval, circular,semi-circular, concave, convex, triangular, square, rectangular and thelike. The electrodes may each have a diameter of 2-10 mm. As anotherexample, the electrode gap may be increased when it is desirable toprovide better resolution of large signals, and closer together forbetter resolution of small signals. The electrode space, size and gainmay be adjusted to locate different types of leads. For example, theelectrodes may be spaced wider apart (e.g., inter-electrodes gap of 2-4inches, 3 inches) to detect low amplitude stimulation outputs fromelectrodes deep inside the patient (e.g., 7-10 inches below thesurface). Electrodes (e.g., the electronics discussed in connection withFIGS. 3 and 5) may be spaced with a medium inter-electrode gap (e.g.,2-4 cm, 2½ cm) to sense high amplitude stimulation outputs fromelectrodes deep inside the patient. Electrodes may be spaced near onanother with a narrow inter-electrode gap (e.g., 3-6 mm, 5 mm) to senselow amplitude stimulation outputs from electrodes near the skin surface(e.g., a lead on the T5 to T9 vertebrae).

FIG. 4C illustrates a probe 455 with a skin contact surface 456 havingan array of surface electrodes 458-463 distributed about an opening 465through the probe 455. The electrodes 458-461 are aligned along alongitudinal scan axis 467 and electrodes 462-463 are aligned along alateral scan axis 469. Electronics 466 are located in a handle 464 thathas a physical cable 468 joining the probe 455 to an external detector.All or a portion of the electrodes 458-463 may be used to measuresignals. For example, signals from different pairs of the electrodes458-463 may be compared to produce multiple comparator signals. Thepairs of electrodes 458-463 may be configured to be sensitive todifferent types of electrodes, different amplitude signals and/ordifferent depth ranges.

The electrodes 466 may switch between subsets of the electrodes 458-463to search for different types of signals at different depths. Forexample, signals from electrodes 461 and 460 may be compared initiallyuntil the probe nears a location of the lead. Signals from electrodes458 and 459 may be compared in response to a determination that adifference signal for electrodes 460, 461 reach a certain level. Signalsfrom electrodes 462 and 463 may be compared at the same time as signalsfrom electrodes 458 and 459 to yield lateral and longitudinal positioninformation, respectively.

FIG. 4D illustrates a probe 475 with a bottom skin contact surface 476having a two dimensional array of electrodes 478 arranged in rows andcolumns. Electronics 486 are in the handle 484. The top surface of theprobe 475 includes one or more motion indicators, such as an array ofLEDs 480. The LEDs 480 are controlled by the electronics 486 based onmeasured signals from one or more of the electrodes. The LEDs 480 lightup to provide the user with information for which direction the probe475 should be moved to be centered over the lead. As another option, theLEDs 480 may provide information to enable the user to place a marker481 or 483 along the edge of the probe at a center of the lead, at adistal tip of the leads, over a failed electrode on the lead and thelike.

FIG. 4E illustrates a top plan view of a probe 490 formed in accordancewith an embodiment. The probe 490 includes a display 492 and positionadjustment output, such as LEDs 493, 494 located on the upper or topsurface of the probe 490 opposite to the skin contact surface. Theoutput (e.g., LEDs 493 and 494) turn on/off to form a series of bars toindicate where the lead is relative to a center or edge marker on theprobe 490. More or few bars in the LEDs 493 and 494 light up as theprobe 490 moves to a position above or aligned with the lead. A portionof the LEDs 493 and 494 are shown with cross-hatching to illustrate LEDsthat are on.

The display 492 may display various additional information. For example,the display may show the type of lead identified, a graphic of the leadtype, which electrode(s) has failed, lead parametric properties (e.g.,pulse width, pulse shape, pulse amplitude, frequency, mode) and thelike. The display 490 may present everything discussed herein inconnection with any other display in the system. AS one example, thedisplay 492 may illustrate images resembling the one or more of theimages shown in FIGS. 2A, 2B and 26 depending upon the lead detected.

The probe 490 also includes a user interface (U/I) 495 which may be atouch sensitive screen, keypad, buttons, knobs and the like. The U/I 495is configured to accept inputs from the user to control modes andoperation of the probe 490.

FIG. 5 illustrates a comparator circuit 500 utilized within the SPC 312in accordance with an embodiment. In FIG. 5, the comparator circuit 500may be implemented as an operational amplifier 502. In the example ofFIG. 5, the amplifier 502 is an amplifier AD624 provided by AnalogDevices and having sixteen input terminals. Input terminals 1-2represent the inputs for receiving the measured signal along lines 314,315 (FIG. 3) from the surface electrodes 304-305. Input terminals 3, 11,13 and 16 may be interconnected with one another in various manners todefine an amount of a gain to be exhibited by the amplifier 502. Inputterminals 4-8 are coupled to ground and positive and negative DC powersupplies to provide the operational range for the amplifier 502.Terminal 9 represents an output terminal that produces a differencesignal representing the difference between the measured signals receivedat terminals 1 and 2, and as determined by the gain defined by theinterconnection of terminals 3, 11-13 and 16. By way of example only,when input terminals 16 and 12 are connected together, and inputterminals 11 and 13 and 3 are connected together, this combination setsthe gain of the amplifier at 1000. By adjusting the interconnection ofterminals 3, 11-13 and 16, the gain of the amplifier may be programmedto different levels such as between 1, 100, 200, 500 and 1000. The gainmay be switched under user control such as through the user interface332 or 495. Optionally, the gain may be switched automatically by thecontroller 336 and/or SPC 312, such as periodically, randomly or basedon a level of the companies signal. The amplifier 502 provides low noise(e.g., 0.2 microvolts peak to peak between 0.1 Hz to 10 Hz). Theamplifier 502 also affords low non-linearity, high CMRR, low inputoffset voltage, and low input offset voltage drift.

In accordance with at least one embodiment, the comparator 500 withinthe probe 302 is able to capture relatively small current signals, suchas when one milliamp is delivered from an implanted electrode that ispositioned between 8 and 10 inches away from the skin surface and thusaway from the surface electrodes. The lead information may include agraph illustrating a capacitive curvature of the signal that is detectedat the probe and presented on the display.

The probe 302 affords a tool for design research and patient diagnosisof mechanical movement for electrical issues experienced by implanted NSdevices and NS leads. When a known electrode pattern is present, thelead information may utilize inverting and non-inverting inputs to thecomparator 500 to determine the polarity of a field and display ofpositive or negative pulse.

It should be recognized that alternative circuit designs and componentsmay be utilized in place of the comparator 500. Optionally, multiplecomparators 500 may be used when multiple electrode pairs are providedin the probe 302. Certain comparators 500 may be configured to searchfor different types of signal or depth electrodes.

FIG. 6 illustrates an example of a difference signal that may be outputby the comparator 500 of FIG. 5 as the probe 302 is moved along the skinsurface 14 relative the NS lead 408. FIG. 6 illustrates one exemplarytype of lead information that may be displayed to a user on the display334 (FIG. 3). The graph 600 represents a two-dimensional field strengthgraph. The graph 600 plots voltage in millivolts along the vertical axis602 and distance in the probe scan direction along the horizontal axis604. The distances 604 are denoted in half inch increments, while thevoltages along the vertical axis 602 are denoted in 0.5 mV increments.The distances along the horizontal axis 604 are measured along a probescan direction 430 that extends generally parallel to the longitudinalaxis 409 of the lead 408. The data points within the graph 600 generallycorrespond to the difference in the field strength at the central axis454 that extends perpendicular to the patient engaging surface 350 ofthe probe 302. The central axis 454 is substantially centered betweenthe electrodes 304 and 305.

The central axis 454 represents the center point of sensitivity for thecomparator 500 between the electrodes 304 and 305. As the probe 302 ismoved along the skin surface 410, the difference signal between themeasurements at electrodes 304 and 305 fluctuates as shown. By way ofexample, when the central axis 454 of the probe 302 is 0.5 in away fromthe eighth electrode 428 on the lead 408, a difference signal of 0.060mV is measured (see data point 621). As the probe 302 is moved closer tothe electrodes 421-428, the difference between the signals sensed atelectrodes 304 and 305 reduces. For example, when the central axis 454of the probe 302 is aligned with electrode 428, the difference signalequals a negative 0.052 mV. When the central axis 454 of the probe 302is centered over electrode 424, the difference signal is measured to bea negative 0.143 mV.

It should be recognized that the measurements and distances illustratedin FIG. 6 are simply exemplary and will vary depending upon thearchitecture of the probe, position of the lead, type of lead, pulseconfiguration, pulse amplitudes and the like.

In the example of FIG. 6, as is illustrated, the comparator 500 willfind a strongest point in the electrical field strength produced by thelead 408 when the surface electrodes 304, 305 are positioned over thecenter region of the set of implanted electrodes 421-428 that areoutputting stimulation pulses. The example of FIG. 6 may represent anexemplary implementation in which an SCS electrode is implemented andthe highest field amplitudes are recorded between designated vertebrae.

FIG. 7 illustrates an alternative embodiment in which a probe 702 isutilized to sense a patch lead 708. The patch lead 708 includes aplurality of implanted electrodes 721 that are arranged in atwo-dimensional array of rows 760 and columns 762 across the front faceof the lead body. A distal portion of a probe 702 is positioned againstor proximate to the surface of the patient's skin 710. The probe 702includes two or more surface electrodes 704-705 that are separated by aninter-electrode gap 752 and arranged on opposite sides of a center axis754. The probe 702 is moved in two dimensions as denoted by longitudinaland lateral scan directions 730 and 731 along the surface 710 to collectmeasured signals representative of the stimulus output from the patchlead 708.

The probe 702 may be moved in the longitudinal scan direction 730 whichis generally parallel to the longitudinal axis 709 of the patch lead 708to collect one type of lead information, such as longitudinal position.The probe 702 may be moved in the lateral scan direction 731 which isgenerally parallel to the transverse axis 711 of the patch lead 708 tocollect another type of lead information, such as lateral position. Asthe probe 702 is moved back and forth in the direction of 730, leadinformation is collected, such as to identify the longitudinal center ofthe lead 708 as denoted by dashed line 713. The probe 702 may be movedback and forth along the lateral scan direction 731 until identifyinglead information that denotes the lateral center of the lead 708 asdenoted by dashed line 715.

FIG. 8 illustrates a process implemented in accordance with anembodiment to detect and analyze implanted leads and NS devices.Beginning at 802, the NS device is set into a desired mode of operation.For example, the NS device may be set to deliver a predetermined pulseor pulse sequence once or repeatedly from a single electrode, from asubset of the electrodes, all electrodes or otherwise. Once the NSdevice begins producing a stimulus output in accordance with thesettings at 802, the lead detection probe is positioned against thepatient skin in a region believed to be generally proximate to theimplanted lead.

At 806, measurement signals are collected from the electrodes within theprobe. At 808, the measured signals are analyzed to obtain implantedlead information. At 810, the lead information is presented to the userin a desired format and is recorded in the memory of the detector. Forexample, the lead information may be presented as a graph or numericdata. Alternatively, the lead information may be presented as analyticaldata, such as indicating pulse width, frequencies, amplitudes, pulsesequences, modes of operations and the like. At 812, the position of theprobe is adjusted. The operations at 806-812 are continuously repeatedin a real-time manner such that the user is able to move the probecontinuously over the surface of the patient and obtain substantiallycontemporaneous real-time information about the lead and the NS device.

The presenting operation may include displaying to the user a graphicalrepresentation of the measured stimulation output including a pulsesequence having at least one pulse void therein corresponding to alocation in the pulse sequence associated with a failed electrode. Thepresenting operation may include displaying to the user a graphicalrepresentation of a measured pulse sequence that includes a blank areain the pulse sequence where a pulse should have been measured, but didnot occur due to a faulty electrode. The presenting operation mayinclude co-displaying measured and programmed stimulation outputs forcomparison by the user to determine where a fault exists.

The process of FIG. 8 utilizes one or more instrumentation amplifierswith pairs of closely spaced electrode inputs (electrode #1 and 2) and athird fixed electrode (electrode #3 attached to the foot or arm) forgrounding purposes. The two closely spaced electrodes #1 and 2 are afixed distance from each other and moved along the skin of the humanbody to locate and display stimulation. This affords a tool forexternally locating electrodes, diagnosing and displaying the actualreal time output of electrical implantable devices implanted within thepatient. This can be done by contacting the skin of the patient with theamplifier's electrodes then moving the amplifier electrodes 1 and 2closer to the strongest point of stimulation by observing the amplifiersoutput amplitude increase as the amplifier electrodes move closer to thestrongest point of stimulation. The electrical detector or amplifier canlocate and display the current capacitive and resistive characteristicsof stimulation with a high level of resolution and accuracy portrayed ona display. The device may detect and/or display a 1 mA signal at adistance of 8.75 inches from the source. The higher the stimulatoroutputs, the better the resolution becomes at large distances.Typically, at 4 mA and up, the device exhibited high resolution from8.75″. The larger the electrode pattern, the higher the resolution forsmaller amplitude outputs. The closer the amplifier electrodes movetowards the source the higher the amplifier's output amplitude(amplified stimulation). This gives an indication of distance versusamplifier output amplitude. The pulse width and frequency remain aconstant per the programmed parameters of the NS device. This amplifierutilizes variable gain adjustments so the entire amplitude of the signalcan be displayed when the source stimulation amplitude reaches higherlevels. The accuracy of the programmed parameters pulse width,frequency, and discharge mode, outputted from the amplifier is wellwithin our product specifications.

FIG. 9 illustrates a process carried in connection with identifyingfaults in leads, such as electrodes that operate intermittently or fail.Beginning at 900, the process sets the NS device to a faultidentification test mode. The fault identification test mode may beprerecorded in the NS device. Optionally, the fault identification testmode may be transmitted to the NS device from an external programmer orfrom the external test device described above in connection with FIGS.3-8.

Once the NS device is set to the test mode, at 902 the NS device beginsdelivering one or more stimulation output sequences associated with thetest mode. For example, a single test mode may include delivering asequence of stimulation outputs from an individual electrode on the NSlead. Alternatively, the sequence may involve delivering stimulationoutputs from set combinations of electrodes on the NS lead. Thecombinations of electrodes, by way of example only, may includedelivering pulses from set combinations of electrodes simultaneously.Alternatively, the sequence may include delivering pulses from differentelectrodes in a predetermined sequence with predetermined delaystherebetween. At 902, a stimulation sequence from the test mode isrepeating delivered.

At 904, the external test device measures stimulation outputs throughthe external probe (e.g., 302). At 904, measurement signals arecollected by the external probe and stored in connection with thecurrent stimulation sequence being delivered by the NS device. Once asufficient number of measured signals are collected and stored inconnection with the stimulation outputs produced by the currentstimulation sequence, flow moves to 906 where it is determined whetheradditional stimulation sequence exists within the current test mode. Anindividual test mode may include a series of stimulation sequences. Forexample, for a lead having eight electrodes arranged along the length ofthe lead, a test mode may include a separate stimulation sequenceassociated with each of the eight electrodes. Hence, during a firstiteration through the operations at 902 and 904, a first stimulationsequence may deliver a series of pulses only from the first electrode.

At 906, it would then be determined whether additional stimulationsequences need to be delivered from the other seven electrodes upon thelead. The operations at 902-906 are iteratively performed, such that aseparate stimulation sequence would be implemented for each of the eightelectrodes in the present exemplary lead. At 906, when it is determinedthat additional stimulation sequences are to be tested, flow moves to908 where the process steps to the next sequence. Flow then returns to902 and the NS device delivers the next stimulation sequence from thetest mode. At 906, after all of the stimulation sequences for thecurrent test mode have been delivered and measured signals collected andstored in connection therewith, flow moves to 910. At 910, the measuredsignals associated with each of the stimulation sequences are thenanalyzed. Various types of analysis may be performed at 910. Forexample, the measured signals from each of the stimulation sequences maybe analyzed separately to determine whether each electrode upon a leaddelivered the desired number of pulses with the desired pulse amplitude,pulse width, pulse timing and the like. Alternatively, the measuredsignals from the stimulation sequences may be analyzed in pulse shape,temporal delivery, correlation and the like.

At 912, the results from the analysis at 910 are presented to the user.For example, at 912, the lead fault results may be presented to the userby informing the user that an individual electrode or electrode on alead have remained open and did not deliver expected stimulationoutputs. Alternatively, the lead fault results may inform the user thatone or more of the electrodes operated intermittently, namely deliveringsome expected stimulation output pulses but not all intended stimulationoutput pulses. As a further result, the lead fault result may inform theuser that pulse amplitudes or pulse shapes were not proper whendelivered by one or more electrodes. The lead fault results may identifyspecific electrodes on a lead that exhibit particular faults, or simplyindicate that one or more of the electrodes exhibit a fault withoutidentifying the specific electrode exhibiting the fault. As a furtheroption, the lead fault results may includes likelihoods of probabilitiesthat a particular fault has occurred. For example, when identifying aparticular fault, the results may inform the user that there is a highlikelihood that electrode number one is exhibiting an intermittentbehavior or is open. As another example, the lead fault results mayinform the user that there is a medium likelihood that one of electrodesthree through six are open. Other types of results may be presented tothe user depending upon a particular type of electrode, a particulartype of lead, the position of the lead and the like.

FIGS. 10A-10C illustrate examples of how lead information may bepresented on the display 334 or 492. FIGS. 10A-10C illustrate graphs1002-1004 of comparator signals resulting from the comparison of two ormore measured signals. The graphs 1002-1004 indicate time along thehorizontal axis 1006A-C and voltage along the vertical axis 1008A-C. InFIG. 10A, the vertical axis 1008A is separated into 500 mV increments,while the horizontal axis 1006A is separated into 100 uSec increments.

FIG. 10A illustrates a pulse 1010 output by the lead and sensed by thesurface electrodes. The pulse 1010 has a width 1012 of approximately 91uSec, amplitude 1014 of approximately 1.16V. The pulse 1010 includes aleading edge 1020, trailing edge 1022, tail 1024 and other parametricproperties that may be of interest and may be measured. The parametricproperties of the pulse may be measured manually from the display by auser or may be automatically measured by the detector. The pulse 1010 isdelivered from one electrode, a subset of electrodes or collectivelyfrom all of the electrodes on the lead. By analyzing the amplitude,pulse width, pulse shape, pulse leading edge, pulse trailing edge, tailand the like, a user may determine whether the active electrode(s) aredelivering a stimulation output with the desired parametric properties.The display may also present additional lead & device relatedinformation 1030 such as the setup or mode 1032 in which the device ispresently operating and the like. When a single electrode or a subset ofelectrodes are being used to deliver pulse 1010, the lead and devicerelated information 1030 may identify which individual electrode orelectrodes are currently generating a stimulation output. For example,the detector may analyze the parametric properties of interest from thepulse and may output the analysis as lead information on the displaysuch as in analytic data area 1034.

FIG. 10B illustrates a graph 1003 in which the vertical axis 1008B hasthe same time scale as in FIG. 10A, but the horizontal axis 1006B hasbeen adjusted to a different time scale spanning a longer period of timethan in FIG. 10A. The vertical axis 1008B is separated into 500 mVincrements, while the horizontal axis 10068 is separated into 2 mSectime increments. FIG. 10B illustrates a pulse sequence 1050 output bythe lead and sensed by the surface electrodes. The pulse sequence 1050includes a series of pulses 1052 successively output by the sameelectrode or electrodes. The pulses 1052 have a width of approximately100 uSec, amplitude of approximately 1.16V and a frequency of 129.5 Hz.Each of the pulses 1052 includes a leading edge, trailing edge, tail andother parametric properties that may be of interest and may be measured.The parametric properties may also include frequency, duty cycle and thelike. The pulse sequence 1050 is delivered from One electrode, a subsetof electrodes or collectively from all of the electrodes on the lead. Byanalyzing the frequency, duty cycle, amplitude, pulse width, pulseshape, pulse leading edge, pulse trailing edge, tail and the like, auser may determine whether the active electrode(s) are delivering astimulation output with the desired parametric properties. When a singleelectrode or a subset of electrodes are being used to deliver pulsesequence 1050, the lead and device related information may identifywhich individual electrode or electrodes are currently generating astimulation output.

The detector measures the parametric properties of interest from thepulse sequence and may output this lead information on the display suchas in analytic data area 1054.

FIG. 10C illustrates a graph 1004 in which the vertical axis 1008C andhorizontal axis 1006C have different time scales than FIG. 10A. Thevertical axis 1008C is separated into 20 mV increments, while thehorizontal axis 1006C is separated into 2.000 mSec time increments. FIG.10C illustrates a pulse sequence 1070 output by the lead and sensed bythe surface electrodes. The pulse sequence 1070 includes a series ofpulses 1072 successively output by the same electrode or electrodes. Thepulses 1052 have a width of approximately 80.00 uSec, amplitude ofapproximately 66.9 mV and a frequency of 129.5 Hz.

FIG. 11 illustrates a process carried in connection with identifyingshort circuits in an NS device header. When a short circuit occurs inthe header, this may lead to electrodes failing to operate at all,operating intermittently or delivering pulses having an improper pulseshape (e.g., low pulse amplitude, faulty pulse leading edge, faultypulse trailing edge and the like). Beginning at 1100, the process setsthe NS device to a header short circuit identification test mode. Theheader short circuit identification test mode may be prerecorded in theNS device. Optionally, the header short circuit identification test modemay be transmitted to the NS device from an external programmer or fromthe external test device described above in connection with FIGS. 3-8.

Once the NS device is set to the test mode, at 1102 the NS device beginsdelivering one or more stimulation output sequences associated with thetest mode. For example, a single test mode may include delivering a setor sequence of stimulation outputs from an individual electrode on theNS lead. Alternatively, the set or sequence may involve deliveringstimulation outputs from set combinations of electrodes on the NS lead.The combinations of electrodes, by way of example only, may includedelivering pulses from set combinations of electrodes simultaneously.Alternatively, the set or sequence may include delivering pulses fromdifferent electrodes in a predetermined sequence with predetermineddelays there between. At 1102, a stimulation set or sequence from thetest mode is repeating delivered.

At 1104, the external test device measures stimulation outputs throughthe external probe (e.g., 302). At 1104, measurement signals arecollected by the external probe and stored in connection with thecurrent stimulation sequence being delivered by the NS device. Once asufficient number of measured signals are collected and stored inconnection with the stimulation outputs produced by the currentstimulation sequence, flow moves to 1106 where it is determined whetheradditional stimulation set or sequence exists within the current testmode. An individual test mode may include a series of stimulationsequences. For example, for a lead having eight electrodes arrangedalong the length of the lead, a test mode may include a separatestimulation sequence associated with each of the eight electrodes.Hence, during a first iteration through the operations at 1102 and 1104,a first stimulation sequence may deliver a series of pulses only from afirst electrode on the lead. During a second iteration through theoperations at 1102 and 1104, a second stimulation sequence may deliver aseries of pulses only from a second electrode on the lead, and so forth.

At 1106, it is determined whether additional stimulation sequences needto be delivered from the other electrodes upon the lead. The operationsat 1102-1106 are iteratively performed, such that a separate stimulationsequence would be implemented for each of the eight electrodes in thepresent exemplary lead. At 1106, when it is determined that additionalstimulation sequences are to be tested, flow moves to 1108 where theprocess steps to the next sequence. Flow then returns to 1102 and the NSdevice delivers the next stimulation sequence from the test mode. At1106, after all of the stimulation sequences for the current test modehave been delivered and measured signals collected and stored inconnection therewith, flow moves to 1110.

At 1110, the measured signals associated with each of the stimulationsequences are then analyzed. Various types of analysis may be performedat 1110. For example, the measured signals from each of the stimulationsequences may be analyzed separately to determine whether each electrodeupon a lead delivered the desired number of pulses with the desiredpulse amplitude, pulse width, pulse timing and the like. Alternatively,the measured signals from the stimulation sequences may be analyzed forpulse shape, temporal delivery, correlation and the like.

At 1112, the results from the analysis at 1110 are presented to theuser. For example, at 1112, the header short circuit results may bepresented to the user by informing the user that a header short circuithas occurred. Alternatively, the header short circuit results may informthe user that one or more of the header is operating intermittently,namely delivering some expected stimulation output pulses but not allintended stimulation output pulses. As a further result, the headershort circuit result may inform the user that pulse amplitudes or pulseshapes were not proper when delivered by one or more electrodes. Theheader short circuit results may identify specific aspects of the headerthat exhibit particular faults, or simply indicate that the headerexhibits a fault without identifying the specific fault within theheader. As a further option, the header short circuit results mayincludes likelihoods of probabilities that a particular fault hasoccurred. Other types of results may be presented to the user dependingupon a particular type of NS device, a particular type of header or leadand the like.

FIG. 12 illustrates an example of the type of information that may bepresented to the user on the display. In FIG. 12, a display 1202 isillustrated with a group of windows presenting different types ofinformation. The display 1202 includes a device setting window 1204 inwhich the present settings are displayed for the NS device, in order toinform the user regarding how the NS device should operate. The devicesetting window 1204 includes an area 1206 for general device settingsand an area 1208 that indicated the programmed stimulation settings forparametric properties of interest, such as the pulse width, amplitude,frequency and the like. The programmed settings may correspond to thecurrent set or sequence of stimulation outputs, for a single stimulationoutput and the like. A detected output area 1210 is included near theprogrammed stimulation setting area 1208. The detected output area 1210may include a listing of values that were measured by the probe 302 forthe parametric properties of interest, such as the pulse width,amplitude, frequency and the like.

The display 1202 also includes a lead properties window 1212 in whichthe properties of an implanted lead are displayed for the NS lead, inorder to inform the user regarding what type of lead is implanted. Thelead properties setting window 1212 includes an area 1214 for generallead properties (e.g., 9 electrode paddle lead, 12 electrode paddlelead, 8 electrode Lamitrode lead, etc) and measured electrode statusareas 1216, 1218 and 1220 that indicated the information aboutindividual electrodes, such as which electrodes have failed (area 1216),which electrodes are operating intermittently (area 1218) and whichelectrodes are good (1220).

The display 1202 also includes a lead graphical area 1222 that maypresent a 2D or 3D image of the type of lead that is implanted, asillustrated by lead image 1224. The lead image 1224 may include indiciato identify failed and/or faulty electrode(s) such as failed electrode1226. Optionally, a faulty or intermittent electrode may be designatedin the lead image 1224 by indicia 1228 which may represent a boundaryline, border, colored area, flashing portion of the lead image 1224 andthe like.

The display 1202 also includes a programmed stimulation window 1230 thatillustrates a representation of the programmed stimulation output 1232that the NS device is intended to generate. The programmed stimulationoutput 1232 may include one or more pulses 1234, 1236 with theprogrammed pulse width, amplitude, and frequency listed in area 1208.The content of the window 1230 may be varied to inform the user of whatstimulation output(s) the NS device should produce based on the presentmode of operation and programmed settings.

The display 1202 also includes a measured stimulation window 1240 thatillustrates a graphical representation of the measured stimulationoutput 1242 that was measured by the surface electrodes and analyzed bythe SPC 312 and controller 336. For example, the measured stimulationoutput 1242 may correspond to the comparator signal output by theamplifier 500. The measured stimulation output 1242 includes one or morepulses 1246 with the measured pulse width, amplitude, and frequencylisted in area 1210. In the example of FIG. 12, the implanted leadincludes one faulty electrode (corresponding to electrode 1226). Thus,the measured stimulation output 1242 has a pulse void 1244 in the pulsesequence. The pulse void is represented by a blank area in the pulsesequence where a pulse should have been measured, but did not occur dueto the faulty electrode 1226. The measured and programmed stimulationoutputs 1242 and 1232 may be co-displayed side by side, above oneanother or in an overlapped manner. By comparing the measured andprogrammed stimulation outputs 1242 and 1232, the user may readilydetermine where the fault is located.

Optionally, one or more of the windows discussed above may be omitted.Optionally, the content of the window 1240 may be varied to inform theuser of what stimulation output(s) the NS device should produce based onthe present mode of operation and programmed settings.

Embodiments described herein provide a tool useful after implantation tomonitor various parametric properties of the NS system. For example,embodiments permit analysis of the operation of the NS device, such asthe discharge mode, pulse sequency, pulse width and frequency for thestimulation output of the NS device. Further, embodiments herein permitthe NS lead to be located and more specifically, to locate the positionand/or identity inoperative and operative electrodes on the NS lead.After implementation, the potential exists for NS leads to move ormigrate within the patient. Embodiments herein afford a reliable andpractical mechanism to readily identify lead migration. Embodimentsherein afford a reliable and practical method for a physician orrepresentative to locate the lead's position in connection withreprogramming or physical intervention. Once the new position of thelead is identified, the physician then reprograms the lead, such as touse a different set of electrodes on the lead to deliver the stimulusoutput. Embodiments described herein avoid exposing the patient toradiation each time a fluoroscopy is performed, which is not desirable.

Embodiments described herein provide reliable and practical ways toidentify lead malfunctions. Lead malfunctions may occur due to physicalfailure or breaks within the lead conduction and/or electrical failureswithin the NS device. When a physical failure or break causes a lead tooperate intermittently or not at all, embodiments described herein areable to diagnose the intermittent and open leads down to the electrode.

Embodiments described herein provide a tool that enables data loggingfor research to enable patient anomalies to be recorded in connectionwith stimulation outputs while an NS lead is in the patient. Embodimentsdescribed herein provide a tool that informs an EMT that the person hasan implantable device, and informs the EMT of the location of theimplantable device. Embodiments described herein provide a tool thataffords a quick method of determining what type of device the patienthas within them, and the location of the device.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventionwithout departing from its scope. While the dimensions, types ofmaterials and coatings described herein are intended to define theparameters of the invention, they are by no means limiting and areexemplary embodiments. Many other embodiments will be apparent to thoseof skill in the art upon reviewing the above description. The scope ofthe invention should, therefore, be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled. In the appended claims, the terms “including” and“in which” are used as the plain-English equivalents of the respectiveterms “comprising” and “wherein.” Moreover, in the following claims, theterms “first,” “second,” and “third,” etc. are used merely as labels,and are not intended to impose numerical requirements on their objects.Further, the limitations of the following claims are not written inmeans—plus-function format and are not intended to be interpreted basedon 35 U.S.C. §112, sixth paragraph, unless and until such claimlimitations expressly use the phrase “means for” followed by a statementof function void of further structure.

What is claimed is:
 1. An external system to detect an implanted leadcoupled to an implanted neurostimulation device (INSD), the systemcomprising: a handheld probe having electrodes configured to bepositioned external to a surface of a patient and proximate to a regionof the patient having the implanted lead for an INSD, the electrodesconfigured to measure a stimulation output from the implanted lead ofthe INSD; a controller coupled to the electrodes to receive measuredsignals from the electrodes, the measured signals representative of thestimulation output of the INSD, the controller processing the measuredsignals to obtain lead information; and a user interface to present thelead information to a user, the lead information indicative of at leastone of an operation of the lead and a position of the lead.
 2. Thesystem of claim 1, wherein the lead information includes at least one ofdischarge mode, pulse width and frequency for the stimulation output ofthe INSD.
 3. The system of claim 1, wherein the lead informationincludes at least one a presence, signal strength, duration and shapefor the stimulation output of the INSD.
 4. The system of claim 1,wherein the lead information includes at least one electrical occurrenceof, and electrical anomalies in, the stimulation output of the INSD. 5.The system of claim 1, wherein the lead information includes at leastone of i) information to locate the lead in the patient and ii)information to identify improper operation of the lead.
 6. The system ofclaim 1, wherein the external electrodes include first and secondelectrode inputs closely spaced proximate to one another to be movedalong skin of the patient while locating the lead.
 7. The system ofclaim 1, further comprising an amplifier that compares the measuredsignals to obtain a difference signal, the difference signal increasingas the electrodes move closer to a source of the stimulation output. 8.A method to detect an implanted lead of an implanted neurostimulationdevice (INSD), the method comprising: positioning a handheld probehaving electrodes external to a surface of a patient and proximate to aregion of the patient having the implanted lead for an INSD; configuringthe electrodes to measure a stimulation output from the implanted leadof the INSD; receiving measured signals from the electrodes, themeasured signals representative of the stimulation output of the INSD;processing the measured signals to obtain INSD lead information; andpresenting the lead information to a user, the lead informationindicative of at least one of an operation of the lead and a position ofthe lead.
 9. The method of claim 8, wherein the lead informationincludes at least one of discharge mode, pulse width and frequency forthe stimulation output of the INSD.
 10. The method of claim 8, whereinthe lead information includes at least one a presence, signal strength,duration and shape for the stimulation output of the INSD.
 11. Themethod of claim 8, wherein the lead information includes at least oneelectrical occurrence of, and electrical anomalies in, the stimulationoutput of the INSD.
 12. The method of claim 8, wherein the leadinformation includes at least one of i) information to locate the leadin the patient and ii) information to identify improper operation of thelead.
 13. The method of claim 8, wherein the presenting operationincludes displaying to the user a graphical representation of themeasured stimulation output including a pulse sequence having at leastone pulse void therein corresponding to a location in the pulse sequenceassociated with a failed electrode.
 14. The method of claim 8, whereinthe presenting operation includes displaying to the user a graphicalrepresentation of a measured pulse sequence that includes a blank areain the pulse sequence where a pulse should have been measured, but didnot occur due to a faulty electrode.
 15. The method of claim 8, whereinthe presenting operation includes co-displaying measured and programmedstimulation outputs for comparison by the user to determine where afault exists.